Bone plate

ABSTRACT

A bone plate includes a first through hole extending through the plate along a first longitudinal axis from a proximal surface of the plate to a bone-facing distal surface thereof which, when the plate is placed on a target portion of bone in a desired orientation, faces the bone. An outer wall of the first through hole includes three wall sections provided with projections for receiving a screw head of a bone screw. The three wall sections are straight or convex.

PRIORITY CLAIM

The present application is a Reissue of U.S. patent application Ser. No.15/722,775 filed on Oct. 2, 2017, now U.S. Pat. No. 9,974,583; which isa Continuation Application of U.S. patent application Ser. No.13/100,784 filed on May 4, 2011, now U.S. Pat. No. 9,801,669; whichclaims priority to U.S. Provisional Application Ser. No. 61/350,691filed on Jun. 2, 2010. The disclosure of the abovepatent(s)/application(s) is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention generally relates to a bone plate which can befixed to a bone by means of bone screws. More particularly, the presentinvention relates to a bone plate having a through hole with an internalthread to threadably receive a locking bone screw.

BACKGROUND OF THE INVENTION

Bone plates with through holes comprising a cylindrical or conicalinterior thread to receive a locking head bone screw are commonly usedin the field of osteosynthesis. Due to the threaded connection betweenthe head of the bone screw and the through hole in the bone plate thebone screw is firmly anchored in the through hole in the bone plate.However, one problem that can arise is that if the bone screw is notexactly coaxially inserted with respect to the through hole axis thethread of the through hole can be damaged.

SUMMARY OF THE INVENTION

The present invention relates to a bone plate being able to receive atleast a central bone screw in such a way that the thread in the throughhole in the bone plate is not damaged when a bone screw is inserted.

According to the present invention, described is a bone plate with aproximal surface, a bone-oriented distal surface and a through hole thewall of which has three or more straight or convex sections providedwith projections such as thread or thread-like structures for receivinga screw head of a bone screw.

One of the advantages of the bone plate according to the presentinvention include a compact entry for setting at choice bone screwsunder a variable angle is provided in such a way that the thread in thethrough hole in the bone plate is not damaged when a bone screw is notcoaxially inserted with respect to the longitudinal axis of the throughhole. Furthermore, due to the configuration of a through hole with threeor more straight or convex sections, a bone screw inserted through thethrough hole may be angled relative to a longitudinal axis of thethrough hole with a reduction of damage to the threads of the throughhole.

In an exemplary embodiment of the bone plate, the through hole has across-sectional area orthogonal to the longitudinal axis with a centerof the cross-sectional area being centered on the longitudinal axis andwherein each of the three or more straight or convex sections is limitedby two radii intersecting each other in the center and enclosing anangle Ω which is smaller than or equal to 360°/n (where n is the numberof straight or convex sections), as will be described in greater detailbelow.

In a further exemplary embodiment of the bone plate, the through holehas a cross-sectional area orthogonal to the longitudinal axis which isgenerally polygonal, preferably with rounded corners.

In a further embodiment of the bone plate, the through hole tapers in adirection towards a distal surface of the bone plate.

In again a further embodiment of the bone plate, the three or morestraight or convex sections are radially symmetric.

In another embodiment of the bone plate, a thread or thread-likestructure extends over the whole length of the three or more straight orconvex sections.

In another embodiment of the bone plate, the thread or thread-likestructure has a constant depth of thread within the straight or convexsections.

In yet another embodiment of the bone plate the depth of thread of thethread or thread-like structure decreases towards each end of each ofthe straight or convex sections.

In still another embodiment of the bone plate the depth of thread of thethread or thread-like structure decreases outside each end of each ofthe straight or convex sections.

In again another embodiment of the bone plate, the thread or thread-likestructure extends over the whole periphery of the through hole.

In a further embodiment of the bone plate according to the presentinvention, the bone plate comprises two or more peripheral holesconnected to and open to a through hole. The peripheral holes include athread for receiving peripheral bone screws therein. The two or moreperipheral holes are arranged peripherally around the through hole insuch a way that they overlap with the through hole to form a compositehole structure able to receive two or more peripheral bone screwstherein while a central bone screw is received in the through hole.

In a further embodiment of the bone plate each of the peripheral holescomprises a spherical recess penetrating partially into the bone platefrom a proximal surface thereof. The advantage of this configuration isthat a conventional cortex screw with an unthreaded spherical head maybe introduced into such a peripheral hole at an angle relative to thelongitudinal axis selected by the user.

In a further embodiment of the bone plate according to the invention,each of the peripheral holes and the through hole includes a thread forlocking the screw received therein at a fixed angle.

In another embodiment of the bone plate, the peripheral holes includethreading for receiving peripheral bone screws at user selected variableangles relative to the longitudinal axes of these peripheral holes whilethe through hole is configured to receive a central bone screw at afixed angle.

In a further embodiment of the bone plate, the threads of the holesextend over at least half of a circumference of each of the holes.

In still a further embodiment of the bone plate, a number, N, of bolesare arranged at the corners of a central through hole being generallypolygonal with N corners. The polygon defined by the hole axes of the Nholes, when viewed in a cross-section orthogonal to the longitudinalaxis of the through hole, can be a triangle, square, pentagon orhexagon.

In another embodiment of the bone plate the fixed angle of insertion ofbone screws through the peripheral holes is in the range of ±0° to ±20°,preferably of ±8° to ±15° with respect to the longitudinal axis.

In yet another embodiment of the bone plate the pitch of the threads isin the range of 0.30 to 2.00 mm, preferably in the range of 0.5 to 1.0mm.

In again another embodiment of the bone plate the threads are multiplethreads. This allows the advantage that the pitch matches the bonethread pitch.

In still another embodiment of the bone plate the centers of twoadjacent holes are at a distance of 4 to 15 mm from each other.

In a further embodiment of the bone plate the diameter of the holes isin the range of 3 to 10 mm.

In again a further embodiment of the bone plate, an inscribed circle tothe wall of the central through hole has a diameter of 2 to 10 mm,preferably of 3 to 7 mm.

In another embodiment according to the present invention, the bone platecomprises at least one peripheral bone screw wherein the plate is madeof stainless steel and the at last one peripheral bone screw is made ofa CoCr alloy or vice versa. Thus, the advantage can be achieved thatsince the threads are less damaged by the plate according to theinvention there is also less corrosion between plate and screws.

In again another embodiment of the bone plate a hole axis of the atleast one hole is not parallel to the longitudinal axis of the thoughhole and preferably angled relative thereto at an angle of ±5° to ±20°.

In again another embodiment the bone plate comprises more than onethrough hole.

In again another embodiment of the bone plate, the wall of the throughhole has n=3 straight or convex sections.

In a further embodiment a bone plate is provided with a proximalsurface, a bone-oriented distal surface and a through hole with alongitudinal axis connecting the proximal and distal surfaces, whereinthe wall of the through hole has n≥3 non-concave sections provided witha thread or thread-like structures for receiving a screw head of a bonescrew.

According to a further object of the invention a kit for bone fixationis provided comprising a bone plate according to the invention, acentral bone screw and N peripheral bone screws.

In a special embodiment of the kit, the central bone screw comprises ascrew head with an external thread matching the thread or thread-likestructure in the through hole of the bone plate and the N peripheralbone screws comprise a screw head each with an external thread matchingthe thread in the N≥2 holes.

In another embodiment of the kit, the screw head of the central bonescrew is conically or spherically shaped and the screw heads of theperipheral bone screws are conically or spherically shaped.

In again another embodiment the kit comprises more than one central bonescrews with differently shaped screw heads and a number of 2×Nperipheral bone screws with differently shaped screw heads. Thisconfiguration allows the advantage that the surgeon can select between:

-   -   a central bone screw with a conically shaped threaded screw head        that is placed at fixed angle relative to the bone plate;    -   a central bone screw with a spherically shaped threaded screw        head that can be placed at a variable angle relative to the bone        plate;    -   N peripheral bone screws with a conically shaped threaded screw        head that are placed at a fixed angle relative to the bone        plate; or    -   N peripheral bone screws with a spherically shaped threaded        screw head that are placed at a variable angle relative to the        bone plate.

In a further embodiment the kit comprises a bone plate, a central bonescrew with a screw head that is conically or spherically shaped andcomprises an external thread and N conventional cortex screws asperipheral bone screws.

BRIEF DESCRIPTION OF THE DRAWINGS

Several exemplary embodiments of the invention will be described in thefollowing by way of example and with reference to the accompanyingdrawings in which:

FIG. 1 illustrates a perspective view of an exemplary embodiment of thebone plate according to the present invention;

FIG. 2 illustrates the bone plate according to FIG. 1 with an insertedcentral bone screw;

FIG. 3 illustrates a lateral view of the bone plate according to FIG. 2;

FIG. 4 illustrates a cross section through the bone plate according toFIG. 2 ;

FIG. 5 illustrates perspective view onto the top of the bone plateaccording to FIG. 1 with inserted peripheral screws;

FIG. 6 illustrates perspective view onto the bottom of the bone plateaccording to FIG. 1 with inserted peripheral screws;

FIG. 7 illustrates a cross section through the bone plate according toFIG. 5 ;

FIG. 8 illustrates a lateral view of the bone plate according to FIG. 5;

FIG. 9 illustrates a perspective view of another exemplary embodiment ofthe bone plate according to the present invention;

FIG. 10 illustrates a cross section through the bone plate according tothe embodiment of FIG. 9 ;

FIG. 11 illustrates a lateral view of the bone plate according to theembodiment of FIG. 9 ;

FIG. 12 illustrates a top view onto a further embodiment of the boneplate according to the invention;

FIG. 13 illustrates a magnified perspective view of detail A in FIG. 12;

FIG. 14 illustrates a schematic top view of detail A in FIG. 12 ;

FIG. 15 illustrates a schematic top view onto a further exemplaryembodiment of the through hole in the bone plate according to thepresent invention;

FIG. 16 illustrates a schematic top view onto another exemplaryembodiment of the through hole in the bone plate according to thepresent invention;

FIG. 17 illustrates a schematic top view onto again another embodimentof the through hole in the bone plate according to the presentinvention; and

FIG. 18 illustrates a cross-section along line A-A in FIG. 17 .

DETAILED DESCRIPTION

The present invention is directed to a system for the fixation offractured or otherwise damaged bones via one or both of a variable angleinsertion and a fixed angle insertion of a bone screw through a boneplate hole. Specifically, a bone plate according to the presentinvention is provided with a central through hole configured to receivea first bone screw therethrough at any user selected angle relative to alongitudinal axis of the through hole within a permitted range ofangulation. A plurality of second bone screws may also be insertedthrough outlying portions of the bone plate hole, each defining aseparate plate hole axis. The outlying portions of the bone plate holeare formed as substantially circular peripheral holes configured tooverlap and be open to the through hole to form a composite hole havingany of a plurality of shapes depending on the placement and number ofthe peripheral holes relative to the through hole, as will be discussedin greater detail with respect to particular embodiments. The peripheralholes may be configured with holes axes selected so that the second bonescrews may only be inserted therethrough at predetermined anglesrelative to a surface of the bone plate. It is noted that although theperipheral holes and through holes are depicted with predeterminedangles in the system of the present invention, these bone plate holesmay extend through the bone plate at any angle without deviating fromthe spirit and scope of the present invention and may be selected toconform to the requirement of a particular procedure.

FIGS. 1 to 8 illustrate a first exemplary embodiment of the inventioncomprising a bone plate 1 including one through hole 9 and threepartially cylindrical peripheral holes 2 arranged peripherally aroundthe through hole 9 in such a way that they overlap with the through hole9 and are open thereto, as will be described in greater detail below. Itis noted that although the through hole 9 is depicted with a triangularcross-sectional shape, any other cross-sectional shape may be employedwithout deviating from the spirit and scope of the present invention.The bone plate 1 comprises a proximal surface 7 and a bone-orienteddistal surface 8. The through hole 9 has a longitudinal axis 6connecting the proximal and distal surfaces 7, 8, the longitudinal axis6 extending orthogonally to the proximal surface 7. The through hole 9is at least partially bordered by a wall 10 including three convexsections 15 provided with projections such as a thread 5 or thread-likestructures for receiving a central bone screw 30 under a variable angle.As will be described in greater detail later, each of the three convexsections 15 of FIG. 1 is curved with a predetermined radius ofcurvature. In an alternate embodiment (not shown), any number andcombination of the convex sections 15 may be formed with a first radiusof curvature while the remainder of the convex sections 15 may be formedwith a second radius of curvature.

Each of the peripheral holes 2 each has a hole axis 11 extending betweenthe proximal and distal surfaces 7, 8 and are provided with a thread 4for receiving peripheral bone screws 20, as shown in FIGS. 6-8 . Theperipheral holes 2 are arranged peripherally around the through hole 9at equal angles relative to each other. In the embodiment shown wherethree peripheral holes 2 are employed, the axes 11 of the peripheralholes 2, when viewed in a cross-section orthogonal to the longitudinalaxis 6 of the through hole 9, define an equilateral triangle.Furthermore, the three peripheral holes 2 overlap the through hole 9 insuch a way that the peripheral holes 2 and through hole 9 form acomposite hole structure suitable to receive 3 peripheral bone screws20, as shown in FIGS. 5 to 8 and/or one central bone screw 30, as shownin FIGS. 2 to 4 . As shown in FIG. 5 , the peripheral holes 2 each alsocomprise a thread 4, which, in one embodiment of the present invention,may be a multiple thread.

When viewed in a cross-section orthogonal to the longitudinal axis 6 ofthe through hole 9, each of the convex sections 15 is centrallypositioned along a respective corner of an equilateral triangle. Eachconvex section 15 is convexly curved in a direction from the proximalsurface 7 to the distal surface 9 so that an apex of each of the convexsections 15 is located radially outside the through hole 9. A bone screw30 can be inserted into the through hole 9 under a surgeon selectedangle so that a screw axis 33 of the bone screw 30 is offset by an angleα relative to the longitudinal axis 6 of the through hole 9. The throughhole 9 of the present invention may be configured so that the bone screw30 insertable therethrough is smaller, larger or the same size as thebone screws 20 insertable through the peripheral holes 2.

The composite hole structure therefore includes three radiallysymmetrically arranged convex sections 15 centrally located on the sidesof an equilateral triangle and three peripheral holes 2 in the cornersof the equilateral triangle. The axes 11 of the peripheral holes 2 arearranged at a distance from the longitudinal axis 6 which is dimensionedin such a way that the peripheral holes 2 overlap the through hole 9 andextend over an angle of more than 180° between their transitions to thethrough hole 9. The wall 10 of the through hole 9 comprises n=3 wallportions with each wall portion being limited by a transition to theperiphery of a first peripheral hole 2 at one of its ends and by atransition to the periphery of a second peripheral hole 2 at its otherend. In the present embodiment each convex section 15 does not extendover the whole length of the wall portion limited by the transitions.The thread 5 or thread-like structure extends over the whole length ofthe three convex sections 15 with a constant depth of thread. The depthof thread of the thread 5 or thread-like structure decreases betweeneach end of the convex section 15 and each of the two transitions to oneof the peripheral holes 2.

As illustrated in FIGS. 2 to 4 the through hole 9 tapers radially inwardtoward the distal surface 8 of the bone plate 1. A central bone screw 30with a screw axis 33 and a screw head 31 is inserted in the through hole9. The screw head 31 is spherically shaped and comprises an externalthread 32 so that the central bone screw 30 can he inserted into thethrough hole at a user-selected angle α between the screw axis 33 andthe longitudinal axis 6 of the through hole 9.

Instead of a central bone screw 30 comprising a spherically shaped screwhead 31 with an external thread 32 a central bone screw comprising aconically shaped screw head with an external thread could be insertedinto the through hole 9. In the latter case the central bone screw wouldbe inserted into the through hole 9 at a fixed angle (e.g., with thescrew axis and the longitudinal axis 6 of the through hole 9coinciding).

As shown in FIGS. 7 and 8 , the peripheral holes 2 are configured sothat each of the hole axes 11 is angled at approximately 20° relative tothe longitudinal axis 6 of the through hole 9. In another embodiment ofthe present invention, the peripheral holes 2 may be angled at any otherangle relative to the longitudinal axis 6 and may optionally also eachextend along different angles, as those skilled in the art willunderstand.

As illustrated in FIG. 7 each of the peripheral holes 2 tapers radiallyinward towards the distal surface 8 of the bone plate 1. A peripheralbone screw 20 with a screw axis 23 and a screw head 21 is inserted intoeach of the peripheral holes 2. The screw head 21 is conically shapedand comprises an external thread 22 so each peripheral bone screw 20 canbe inserted into one of the peripheral holes 2 at a fixed angle with thescrew axis 23 and the hole axis 11 of the peripheral hole 2 coinciding.

Instead of peripheral bone screws 20 comprising conically shaped screwheads 21 with an external thread 22, peripheral bone screws comprisingspherically shaped screw heads with an external thread may be insertedinto the peripheral holes 2. In the latter case the peripheral bonescrews may be inserted at a user selected variable angle between thescrew axis 23 and the hole axis 11 of the peripheral hole 2.

In FIGS. 9 to 11 another embodiment is illustrated which differs fromthe embodiment of FIGS. 1 to 8 only in that the generally polygonalthrough hole 9 comprises rounded corners instead of the N=3 peripheralholes 2 arranged in the corners. Similarly to the embodiment of FIGS. 1to 8 , the wall 10 of the through hole 9 comprises n=3 convex sections15 which in a cross-section orthogonal to the longitudinal axis 6 arecentrally located on the sides of an equilateral triangle. Each of theconvex sections 15 is convexly curved in a cross-section orthogonal tothe longitudinal axis 6 of the through hole 9 with the apex of eachconvex section 15 located on a middle line orthogonal to one side of theequilateral triangle. Due to the convex sections 15, a bone screw 30 maybe inserted into the through hole 9 under a surgeon selected anglerelative to the axis 6.

The through hole 9 includes three radially symmetrically arranged convexsections 15 centrally located on the sides of an equilateral triangleand three concavely rounded sections in the corners of the equilateraltriangle. The wall 10 of the through hole 9 therefore comprises n=3 wallportions whereof each wall portion extends along one side of anequilateral triangle and is limited by a transition to a first concavelyrounded section at one of its ends and by a transition to a secondconcavely rounded section at its other end. In the present embodimenteach convex section 15 extends over the whole length of the wall portionlimited by the transitions. The thread 5 or thread-like structureextends over the whole periphery of the through hole 9. The depth ofthread of the thread 5 or thread-like structure can decrease in theconcavely rounded sections.

As illustrated in FIG. 10 the through hole 9 tapers towards the distalsurface 8 of the bone plate 1. A central bone screw 30 with a screw axis33 and a screw head 31 is inserted in the through hole 9. The screw head31 is spherically shaped and comprises an external thread 32 so that thecentral bone screw 30 can be inserted into the through hole at auser-selected variable angle α between the screw axis 33 and thelongitudinal axis 6 of the through hole 9.

In FIGS. 12 to 14 another embodiment of the bone plate 1 is illustratedwhich comprises two through holes 9. Similarly to the embodiment ofFIGS. 9 to 11 , the through hole 9 has cross-sectional area orthogonalto the longitudinal axis 6 with a center 14 located on the longitudinalaxis 6 with each of the n=3 convex sections 15 being limited by tworadii intersecting each other in the center 14 and enclosing an angle Ωwhich is smaller than 120°. The wall 10 of each of the two through holes9 comprises n=3 wall portions with each wall portion extending along oneside of an equilateral triangle and limited by a transition to a firstconcavely rounded section at one of its ends and by a transition to asecond concavely rounded section at its other end. Similarly to theembodiment of FIGS. 9 to 11 , each convex section 15 extends over thewhole length of the wall portion limited by the transitions. The throughholes 9 differ from the through hole 9 of the embodiment of FIGS. 9 to11 only in that the thread 5 or thread-like structure does not extendover the whole periphery of the through hole 9. The depth of thread ofthe thread 5 or thread-like structure decreases on each end of theconvex section 15 at the transition between the convex section 15 andthe concavely rounded section in such a way that a portion of theconcavely rounded sections is unthreaded.

As illustrated in FIG. 13 the through hole 9 tapers radially inwardtoward the distal surface 8 of the bone plate 1. Similarly to theembodiment of FIGS. 9 to 11 , a central bone screw 30 with a screw axis33 and a screw head 31 can be inserted in the through hole 9. By using acentral bone screw 30 the screw head 31 of which is spherically shapedwith an external thread 32, the central bone screw 30 may be insertedinto the through hole 9 at a user-selected, variable angle α of thescrew axis 33 to the longitudinal axis 6 of the through hole 9.

FIG. 15 illustrates a further embodiment of the through hole 9 whichdiffers from the embodiment of FIGS. 12 to 14 only in that it comprisesn=4 convex sections 15. Each of the n=4 convex sections 15 is limited bytwo radii intersecting each other in the center 14 and enclosing anangle Ω which smaller than 90°. The wall 10 of each of the two throughholes 9 comprises n=4 wall portions with each wall portion extendingalong one side of a square and limited by a transition to a firstconcavely rounded section at one of its ends and by a transition to asecond concavely rounded section at its other end. Similarly to theembodiment of FIGS. 9 to 11 , each convex section 15 extends over thewhole length of the wall portion limited by the transitions. The thread5 or thread-like structure does not extend over the whole periphery ofthe through hole 9. The depth of thread of the thread 5 or thread-likestructure decreases on each end of the convex section 15 at thetransition between the convex section 15 and the concavely roundedsection in such a way that a portion of the concavely rounded sectionsis unthreaded.

FIG. 16 illustrates again a further embodiment of the through hole 9which differs from the embodiment of FIG. 15 only in that the wall 10 ofthe through hole 9 comprises n=4 straight sections 15 and that the depthof thread of the thread 5 or thread-like structure decreases from amiddle line orthogonal to one side of the square towards the transitionbetween the straight section 15 and each of the concavely roundedsections in such a way that the concavely rounded sections areunthreaded.

FIGS. 17 and 18 illustrate again a further embodiment of the throughhole 9 which differs from the embodiment of FIG. 14 only in that the N=3peripheral holes 2 are configured to receive conventional cortex screws.Each peripheral hole 2 comprises a spherical recess 25 penetratingpartially into the bone plate 1 from the proximal surface 7 and axiallyadjacent to a conically enlarging lower section 26 extending between thespherical recess 25 and the distal surface 8 of the bone plate 1. Due tothe spherical recess 25, a conventional cortex screw with a sphericalhead may be inserted into each of the peripheral holes 2 at auser-selected angle with respect to the axis 11 of the peripheral hole2. The n=3 straight or convex sections 15 of the wall 10 of the throughhole 9 are configured similarly to the embodiment of FIG. 14 .

Although the invention and its advantages have been described in detail,it should be understood that various changes, substitutions, andalterations can be made herein without departing from the spirit andscope of the invention as defined by the appended claims. Moreover, thescope of the present application is not intended to be limited to theparticular embodiments of the process, machine, manufacture, compositionof matter, means, methods and steps described in the specification. Asone of ordinary skill in the art will readily appreciate from thedisclosure of the present invention, processes, machines, manufacture,composition of matter, means, methods, or steps, presently existing orlater to be developed that perform substantially the same function orachieve substantially the same result as the corresponding embodimentsdescribed herein may be utilized according to the present invention.

It will be appreciated by those skilled in the art that variousmodifications and alterations of the invention can be made withoutdeparting from the broad scope of the appended claims. Some of thesehave been discussed above and others will be apparent to those skilledin the art.

What is claimed is:
 1. A kit for bone fixation, comprising: a throughhole extending through a bone plate along a longitudinal axis from aproximal surface to a bone-oriented distal surface which, when the boneplate is positioned on a bone in a desired orientation, faces the bone,an outer wall of the through hole having three non-concave wall sectionsprovided with projections for lockingly engaging a head of a bone screwinserted therethrough and at least one peripheral hole, each peripheralhole overlapping part of the through hole; a central bone screwconfigured to be inserted through the through hole, the central bonescrew including a threaded head sized and shaped to lockingly engage theprojections in the through hole; and at least one peripheral bone screw,each peripheral bone screw being sized and shaped to be inserted througha corresponding peripheral hole.
 2. The kit according to claim 1,wherein a cross-sectional shape of the through hole extendingorthogonally to the plane including the first longitudinal axis ispolygonal with rounded corners.
 3. The kit according to claim 1, whereinthe at least one peripheral bone hole extends through the bone platefrom the proximal surface to the distal surface thereof along acorresponding first hole axis and includes a thread for locking a screwhead of the at least one peripheral bone screw therein, each peripheralhole overlapping a periphery of the through hole to form a compositehole structure configured to receive the at least one peripheral bonescrew through the at least one peripheral hole and the central bonescrew through the through hole.
 4. The kit according to claim 1, whereinthe through hole tapers down in size in a direction from the proximalsurface towards the distal surface of the bone plate.
 5. The kitaccording to claim 1, wherein the projections comprise one of thread andthread-like structure extending over an entire length of each of thewall sections.
 6. The kit according to claim 5, wherein the one ofthread and thread-like structure has a constant depth of thread in thewall sections.
 7. The kit according to claim 5, wherein a depth ofthread of the one of thread and thread-like structure decreases towardsproximal and distal ends of each of the wall sections, the depth ofthread being greatest at a center portion of the wall sections betweenthe proximal and distal surfaces.
 8. The kit according to claim 5,wherein a depth of thread of the one of thread and thread-like structureincreases towards proximal and distal ends of each of the wall sections,the depth of thread being greatest at a center portion of the wallsections between the proximal and distal surfaces.
 9. The kit accordingto claim 1, wherein each peripheral hole comprises a spherical recesspartially penetrating the bone plate from the proximal surface.
 10. Thekit according to claim 1, wherein each peripheral bone screw is lockedat a fixed angle relative to the corresponding hole axis and wherein thethrough hole includes a thread configured to lock a bone screw insertedtherein at an angle relative to the through hole longitudinal axisselected by a user.
 11. The kit according to claim 1, wherein eachperipheral hole includes a thread configured to lock a peripheral bonescrew therein at an angle relative to the corresponding peripheral holeaxis selected by a user and wherein the through hole includes a threadconfigured to lock a bone screw therein at an angle fixed relative tothe through hole longitudinal axis.
 12. The kit according to claim 11,wherein the thread extends over at least half of a circumference of eachperipheral hole.
 13. The kit according to claim 11, wherein the throughhole is polygonal and each peripheral hole is arranged at a corner ofthe through hole.
 14. The kit according to claim 4, wherein centers oftwo adjacent ones of the peripheral holes are separated by a distance of4 to 15 mm.
 15. The kit according to claim 14, wherein the bone plate ismade of a CoCr alloy.
 16. The kit according to claim 13, wherein theperipheral hole axis of a first one of the peripheral holes is orientedrelative to the through hole longitudinal axis at an angle between 5°and 20°.
 17. The kit according to claim 1, further comprising: a secondthrough hole, wherein an outer wall of the second through hole includesthree wall sections which are one of straight and convex.
 18. The kitaccording to claim 1, wherein a cross-sectional shape of the three wallsections in a plane including an axis extending orthogonally to a planeincluding the through hole longitudinal axis is one of straight andconvexly curved toward the through hole.
 19. A kit for bone fixationcomprising: a bone plate comprising a through hole extendingtherethrough from a first surface which, in an operative configuration,faces toward a bone, to a second surface which, in the operativeconfiguration, faces away from the bone, the through hole extendingthrough the bone plate and defined via a wall including at least threenon-concave sections, at least portions of the non-concave sectionsincluding threading and at least one peripheral hole formed between afirst one and a second one of the non-concave sections, wherein thenon-concave sections of the wall are substantially linear; and a centralbone screw configured to be inserted through the through hole, thecentral bone screw including a threaded head sized and shaped tolockingly engage the threading of the non-concave sections.
 20. The kitof claim 19, wherein the through hole tapers from the second surfacetoward the first surface.
 21. The bone fixation kit of claim 19, whereina depth of the threading in the non-concave sections remains constantthroughout a length of the through hole.
 22. A kit for bone fixation,comprising: a through hole extending through a bone plate along alongitudinal axis from a proximal surface to a bone-oriented distalsurface which, when the bone plate is positioned on a bone in a desiredorientation, faces the bone, an outer wall of the through hole havingthree non-concave wall sections provided with projections for lockinglyengaging a head of a bone screw inserted therethrough and at least oneperipheral hole overlapping part of the through hole, wherein the atleast one peripheral hole includes threading; and a central bone screwconfigured to be inserted through the through hole, the central bonescrew including a threaded head sized and shaped to lockingly engage theprojections in the through hole.
 23. The bone fixation kit of claim 22,wherein the threading of the at least one peripheral hole is configuredto lock a threaded head of a bone screw therein at an angle fixedrelative to an axis of the at least one peripheral hole.
 24. The bonefixation kit of claim 22, wherein a depth of the projections in thenon-concave sections is constant throughout a length of the throughhole.